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A heat exchanger designed to cool a liquid such as water has a boiler with several upright heat-transfer tubes on whose inner surfaces the liquid descends in the form of a thin film while a refrigerant such as ammonia or a Freon rises within the boiler. To generate the thin films the liquid to be co

A heat exchanger designed to cool a liquid such as water has a boiler with several upright heat-transfer tubes on whose inner surfaces the liquid descends in the form of a thin film while a refrigerant such as ammonia or a Freon rises within the boiler. To generate the thin films the liquid to be cooled is collected in a storage vessel above the boiler into which the heat-transfer tubes project. Each of these open-topped tubes contains an insert with a frustoconically diverging bottom part approaching the inner tube surface to within a fraction of a millimeter. The bottom part of the insert has an acute-angled peripheral edge insuring the detachment of the liquid from its surface. The several inserts are suspended from a vertically reciprocable piston rod forming part of a pneumatic jack whose alternate pressurization is controlled by a relay in response to two microswitches actuated by cams on the piston rod and to two level sensors ascertaining the liquid level in the storage vessel. A rise in the liquid level detected by the first sensor, due to a clogging of the annular gap by solids present in the liquid to be cooled, initiates such vertical reciprocation; if that fails to dislodge the accumulated solids, as determined by a further rise in liquid level detected by the second sensor, the inserts are fully extracted from their tubes so that also larger chunks can be swept away, causing the liquid volume to decrease to a normal amount.

대표청구항 ▼

A tube assembly for a falling film heat exchanger comprising: a metal tube; a synthetic resin sleeve fitted snugly over said tube and formed with an inwardly extending shoulder abutting an upper end of said tube, said sleeve being open upwardly over its entire cross section; an insert received in sa

A tube assembly for a falling film heat exchanger comprising: a metal tube; a synthetic resin sleeve fitted snugly over said tube and formed with an inwardly extending shoulder abutting an upper end of said tube, said sleeve being open upwardly over its entire cross section; an insert received in said sleeve and said tube and having: a frustoconical lower portion diverging outwardly toward and within an inner wall of said tube and defining therewith a narrow annular gap from which a liquid film can pass downwardly along said inner wall of said tube, a solid cylindrical stem extending upwardly from said frustoconical lower portion, and a plurality of angularly equispaced guide webs extending radially outwardly from said stem lying in respective axial planes, said stem having a free end extending above said webs and said sleeve, said guide webs having upper portions slidably engaging an inner wall of said sleeve for accurately positioning said edge relative to said inner wall of said tube, lower portions extending into said tube, and steps respectively between each upper portion and lower portion of each guide web engaging said shoulder for limiting the penetration of the insert into said tube, said insert being integrally molded from a synthetic resin and is separate from said sleeve, said frustoconical lower portion being formed with a downwardly widening conical cavity terminating in an outwardly extending bevel defining said edge.